The separation and analysis of chemical substances provides valuable quantitative and qualitative data for use by researchers and health care providers. Many assaying techniques have been developed which utilize sensitive chemical and instrument tests to detect the presence and amounts of normal and abnormal components of biological fluids. For example, the analysis of blood samples yields information which is critical to the proper diagnosis and subsequent treatment of many illnesses. To perform such a blood test, a sample of blood is obtained and is then prepared for analysis and, of course, there are many different analytical procedures currently available. Preparation of the blood sample typically requires that the various sample components be separated from each other in order to obtain a more nearly homogenous specimen for testing and evaluation, such as isolating blood serum which is to be analyzed. The amount of serum protein, protein-bound iodine, sodium, triglycerides, salicylate, uric acid, and many other components may be determined through the separation of a blood sample and subsequent analysis. Hence, fast and accurate methods of sample preparation are highly desirable.
The need for conveniently and efficiently dispensing liquid, such as a biological fluid, from a test tube or the like is encountered many times a day by laboratory workers. The opening or mouth of the test tube must be large enough for the material to be initially placed into the test tube. However, this proves to be a hindrance in the dispensing of fluid from the test tube since, quite frequently, too much fluid is dispensed from the test tube as the test tube is inverted. Conventional dispensing techniques, such as decanting a liquid from a precipitate using a stirring rod, requires considerable manipulative skill and does not provide adequate control over the volume of decanted liquid to be dispensed. Providing a lip or a spout on a test tube or other container may help direct the flow of fluid somewhat, but meaningful volume control is still not attained and splashing typically occurs. The transfer of liquids from a test tube to a specimen test area is more accurately controlled with a pipette; however, pipettes must be routinely cleaned and, of course, the pipetting operation must be performed each time a sample is to be dispensed.
Particularly in the environment of preparation and dispensing of biological fluids, a simple and convenient method and apparatus are needed so that a fluid may be easily dispensed from a container, such as a test tube. The present invention provides such a method and apparatus, whereby virtually any liquid may be easily dispensed from a test tube without the use of the complicated pouring techniques and complex devices.
It has been heretofore suggested to provide a flexible dispenser on a container such as a bottle. This is illustrated, for example, in British Patent Specification No. 659,217, published Oct. 17, 1951, and French Patent No. 1,333,865 of June 24, 1963. Each of these documents discloses a flexible, squeezable dispenser to be attached to a container. In addition, British Patent Specification No. 521,237 of May 19, 1940 describes and illustrates a closure for bottles or containers which is not only removable, but which also includes an internal extension which may engage a cork to close and seal the container.
When a dispenser is attached to a test tube and the test tube is inverted so that liquid may be dispensed, the fluid in the test tube tends to flow toward the dispenser, and the inertia of the moving fluid within the test tube often causes the fluid in the test tube to be dispensed prematurely. This phenomenon is referred to as "spitting" or "jetting." It is one of the principal purposes of the present invention to provide an improved dispensing means which eliminates the problem of "jetting," thus providing substantially improved control over the amount of biological fluid to be dispensed.